Long-term effect of physical activity on energy balance and body composition

Abstract

We studied the effect of an increase in physical activity on energy balance and body composition without interfering with energy intake (EI). Sixteen women and sixteen men, aged 28-41 years, body mass index 19 4 2 6 4 kg/m*, not participating in any sport before the start of the experiment, prepared to run a halfmarathon competition after 44 weeks. Measurements of body composition, EI and energy expenditure (EE) were performed before (0 weeks), and 8, 20, and 40 weeks after the start of training. Body composition was measured with hydrodensitometry and isotope dilution, and EI with a 7 d dietary record. EE was measured overnight in a respiration chamber (sleeping metabolic rate (SMR)) and in a number of subjects over 2-week intervals with doubly-labelled water (average daily metabolic rate (ADMR)). ADMR showed an average increase of 30 % in both sexes from the start of training onwards while SMR tended to decrease. El showed a tendency to drop from week 20 to week 40 in the men and a tendency to increase from week 20 to week 40 in the women. Body mass (BM) did not change in both sexes until the observation at 40 weeks when the median value of the change in men was -1.0 kg (P < 0-01 ;Wilcoxon signed-rank) while the corresponding change of -0.9 kg in the women was not statistically significant. Body composition changes were most pronounced in men as well. Based on changes in BM, body volume and total body water, men lost 3.8 kg fat mass (FM) (P < 0,001 ; Wilcoxon signed-rank) and gained 1.6 kg protein mass (P < 0.01 ; Wilcoxon signed-rank) while the corresponding changes in women were 2.0 kg (P < 0.05; Wilcoxon signed-rank) and 1.2 kg (P < 0.05; Wilcoxon signed-rank). In men the loss of FM was positively correlated with the initial percentage body fat (Pearson r 0.92, P < 0 001). In conclusion, body fat can be reduced by physical activity although women tend to compensate for the increased EE with an increased EI, resulting in a smaller effect on BM and F M compared with men.Physical activity : Energy balance : Body compositionIn the Western world many people struggle with overweight due to excessive fat storage. It is obvious that this form of overweight is a consequence of a discrepancy in the energy balance but it is not known whether a raised food intake or a lowered metabolic rate is responsible. A small but persistent bias in the energy balance can have a large effect and the techniques for measurement of both energy intake (EI) and energy expenditure (EE) may not be sufficiently precise to detect this.

Exercise and Weight Loss: What Is the Evidence of Sex Differences?

“…In contrast, women in the exercise group had a small weight gain (approximately +0.6 kg), while the control group had a much larger weight gain (approximately 3.0 kg). This is supported by another study showing that 40 weeks of exercise training significantly lowered weight (approximately -1.0 kg; P<0.01) in men [17]. In contrast, exercise training did not significantly promote weight loss (approximately -0.9 kg, P>0.05) in women [17].…”

“…This is supported by another study showing that 40 weeks of exercise training significantly lowered weight (approximately -1.0 kg; P<0.01) in men [17]. In contrast, exercise training did not significantly promote weight loss (approximately -0.9 kg, P>0.05) in women [17]. Despite men and women responding differently to exercise, the clinical meaningfulness of~1 kg of weight loss is questionable.…”

The comparative and cumulative effects of a dietary restriction and exercise on weight loss

“…Differences may be due to a reporting bias or it may be that men and women are differentially affected by components of the energy balance equation. Exercise has been shown to be more efficacious in men compared with women, 18,19 and researchers have speculated that this may be due, in part, to increased energy expended by men at the same level of physical activity as women. 49 It may also be due to locations of storage in men vs women and how quickly it is mobilized from these regions during weight loss (upper body for men and gluteal-femoral region for women).…”

“…Several studies have shown that exercise is more efficacious in reducing weight among men compared with women. [18][19][20] As noted, an investigation of the relative benefits of weight loss behaviors must also take into account the willingness of individuals to adopt various levels of change in each behavior. There has been limited research to-date on patterns of change in exercise and diet when undertaken in the same time frame for weight management.…”

Impact of high-intensity exercise on energy expenditure, lipid oxidation and body fatness

“…29,30 Although some studies have also reported carryover effects of an exercise intervention on resting 31 and basal metabolic rate, 32 others failed to con®rm these ®ndings when measuring sleeping metabolic rate. 33,34 Beyond these observations, it would seem that an exercise challenge has the potential to acutely impact on energy metabolism in the post-exercise period. In fact, it is a well-known fact that exercise generates an excess in post-exercise oxygen consumption, 8,35 an effect which might be substantiated by an increase in exercise intensity.…”